This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This projects aims at elucidating the binding stoichiometry of uPAR, its main physiological ligand, uPA, and modulators of its activity in cellular adhesion mechanisms. The stoichiometry will be studied by the novel N&B approach in live cells using GFP-tagged receptor and ligands. A series of cell lines expressing GFP-uPAR or mCherry-uPAR will be tested for investigating the effect of overexpression of the receptor and the binding kinetics and internalization of the receptor-ligand complexes.